1. Field of the Invention
The present invention relates to a conduit system for the transport of gases of high temperature and high pressure during travel between a plurality of component units of a power station arranged inside a pressure vessel, and more particularly to such a conduit system which is adapted for use in conjunction with the operating units of the main circuit of a gas-cooled nuclear reactor station.
2. Description of the Prior Art
In installations of the aforementioned kind, the gas conduit system has for its purpose to guide the heated, highly pressurized gas which leaves the reactor core to a turbine or to heat exchanging process units, further to distribute the gas to the various other operating units of the circuit, to collect the gas as it leaves these units, and to lastly return it to the reactor core. In view of the fact that even insignificant defects in a nuclear reactor power station may lead to radioactive contamination or irradiation of the surrounding areas of the reactor, all component parts of such an installation are subject to the most stringent requirements concerning their operating safety. For this reason, it is necessary to construct the entire installation, including the gas conduit system, in such a way that no radioactively contaminated gas can escape from the pressure vessel.
From German Offenlegungsschrift No. 2,028,736 there is known a nuclear power station having a closed gas-cooled circuit and featuring, inside a concrete pressure vessel, a high-temperature reactor, a gas turbine unit with compressor, heat exchanging units, as well as the gas conduits which link together the machines, the heat exchanging units, and the reactor core. The machines, heat exchanging units, and the conduits are in this case accommodated inside a machine block of pre-stressed concrete which is separate from the concrete pressure vessel. The only connections between the machine block and the concrete pressure vessel are an explosion- and radiation-proof gas supply conduit and gas return conduit. These two conduits may be constituted of a double-wall steel shell, or they may be jacketed with concrete walls. Other gas conduits, which link the units arranged inside the machine block, are constructed so that they serve as so-called lost forms, with concrete being cast around them at the place of final installation. This method of constructing the gas conduit system has the shortcoming that it precludes inspection and maintenance access to the gas conduits at a later date; it also makes any replacement of defective gas conduit components impossible. A further consideration which weighs against this type of installation is the fact that the elevated gas temperatures which are characteristic of a high-temperature reactor lead to considerable heat stress in the surrounding concrete.
In German Auslegeschrift No. 1,614,610 is likewise disclosed a nuclear power station featuring a concrete pressure vessel, and an associated pressure-tight machine chamber enclosing the turbine, the compressor, and the heat exchanging process units. The entire installation may alternatively also be arranged inside a single concrete structure enclosing two self-contained, pressure-proof chambers, separated from each other by means of a partition wall. In this partition wall are arranged wall conduits for the working gas which are installed directly in the concrete of the partition wall, in the form of insulated concrete ducts covered by a gas-tight steel skin. These conduits, too, are subject to the earlier-mentioned shortcomings: they are unaccessible for servicing or replacement, and the concrete is again subjected to elevated temperature stress, especially around the conduit which transports the heated working gas.